Your friend performed a two-tailed experiment in which n = 20. He couldn't find his t -table, but remembered the t -critical at df = 10.

Your friend performed a two-tailed experiment in which n = 20. He couldn't find his t-table, but remembered the t-critical at df = 10. He decided to compare his t-obtained to this t-critical and determined the results were not significant. Is this ok? Why or why not.